This invention is related to an alloy useful in fusible metal and metal ornament applications, and more particularly, to a jewel metal alloy having bismuth and lead as the major constituents of its composition.
Currently, most alloys fabricated into costume jewelry and the like are principally composed of tin and lead, or are of "pewter" composition, which is an alloy of at least 92% tin, with the balance being antimony and copper. Another particularly popular alloy that has found widespread commercial use has a composition that ranges between 23-36% tin, with the balance being mostly lead. However, the price of tin is high, and thus there is a need for a low-tin or tin-free alloy, which has either equal or superior properties to the high tin alloys already in use.
Most jewel metal ornaments are manufactured by a process in which the metal is cast into rubber molds which are shaped to whatever design is desired. The molds are usually hand made by the manufacturer, while the alloy employed is required to fulfil only general standards, as precise specifications for a metal are practically nonexistent in the industry. The alloy must have excellent fluidity in order that it can be easily cast into a variety of different shapes. The casting temperature of the metal should be as low as practical, so as to prolong the life of the rubber mold, while the porosity of the alloy should be minimal, for a porous alloy will cause the plating chemicals to "bleed out", i.e. the plating electrolyte flowing out of the cast alloy, and consequently damage the finished metal surface. The jewel metal must also be sufficiently strong and durable to withstand the mechanical strains inherent in the manufacturing process, particularly the tumbling and polishing steps. Also, of course, the cost of the alloy should be as low as possible.